I just got to level 52 and was gifted with a brand new, out-of-the-box Masterton. I made a load out just for it.

Masterton
Kunara
Speed Loader
Lightfoot
Remote Mines

I use it when I get bored or in Archives, Facility and Sewers or towards the end of the game - usually when it's time to destroy the black box or when things get into close quarters. It's a monster and I am already on the verge of level 53 and my proxies.

My girl, on the other hand, takes great glee in running up on the box as soon as she can and blasting it into oblivion. She doesn't care how often she gets killed so long as she blasts the box to pieces.